1. Field of the Invention
The present invention relates generally to an improved structure for compact air compressors, and more particularly to a compact air compressor which is easy to assemble and has high air output efficiency.
2. Description of the Prior Art
FIG. 6 shows a conventional air compressor, which comprises a motor 5, a securing plate 6, a transmission gear 7, a compression cylinder 8, and a connecting disk 9. The motor 5 and securing plate 6 are screwably locked together by bolts 50. A guide gear 51 is fixedly provided at the spindle of the motor 5. The horizontal end of the securing plate 6 is formed with a cylinder hole 60 and a plurality of screw holes 61. The vertical end of the securing plate 60 is provided with upper and lower gear holes 62, 63. The upper gear hole 62 allows the passage of a spindle of the guide gear 51 of the motor, whereas the lower gear hole 63 receives a connecting tube 64 and one end of a spindle of the transmission gear 7. A C-clip 65 is used to fasten them in place. Reinforcing ribs 66 are disposed at the joint between the vertical end and horizontal end of the securing plate 6. At the same time, the transmission gear 7 is provided on the securing plate 6 and engages the guide gear 51. One end of the transmission gear 7 is provided with a weight 70. The other end thereof has a connecting rod 71 extending therefrom. The connecting rod 71 is pivotally connected to the bottom of a link 80. The top end of the link 80 is pivotally connected to a piston 82 by means of a shaft 81. The top end of the piston 82 is fitted with a compression block 83 and a ring 84 in sequence. By means of a through lower air hole 85, the top portion of the compression block 83 may be coupled to a packing piece 86 and movably connected with a cover plate 87 assembled into the compression cylinder 8, whereby the compression cylinder 8 may generate a pushing force due to rotation of the motor 5. Furthermore, the upper end of the compression cylinder 8 is connected to the connecting disk 9, which is peripherally provided with a plurality of connecting elements 90. Bolts 91 are passed through round holes 92 of the connecting elements 90 and the screw holes 61 of the securing plate 6 to lock the connecting disk 9, the compression cylinder 8, and the securing plate 6 as a whole. The connecting disk 9 is further provided with an upper air hole 93 which is connected to a packing piece 94 and a cover plate 95. The upper air hole 93 cooperates with the lower air hole 85 of the the piston 82 to achieve the drawing in and discharge of air, the air being output from a guide tube 96 connected to one end of the connecting disk 9.
As can be seen, the conventional air compressor is very complicated in structure and assembly thereof is also difficult. The drawbacks of conventional air compressors are summed up as follows:
1. Air discharge control effects achieved by utilizing displacement of the ring 84 of the compression block 83 inside the compression cylinder 8 are not complete. PA1 2. Assembly is inconvenient and troublesome as the link 80 is coupled to the piston 82 by means of the shaft 81 and the upper end of the piston 82 has the compression block 83 and the ring 84 fitted thereon. And besides, manufacturing costs are relatively high and production speed low. PA1 3. As the securing plate 6 and the compression cylinder 8 are coupled in a separated manner, manufacture of the air compressor is made difficult. Additionally, the securing plate 6 cannot constitute a preferred structure in which the fulcrum is located between the point of force application and the point of resistance. PA1 4. As the transmission gear is provided with a weight, the load borne by the gear from rotation to air intake is relatively large, so that the friction coefficient between pitches increases, which may damage the transmission gear and affect intake and output air pressure.